§20.20Fr. 20
Ἐν τῷ δευτέρῳ τῶν περὶ Κινήσεως· οἰκειότερον δὲ ὅπερ καὶ λέγομεν καὶ ἔστιν, ἐνέργειαν τοῦ δυνάμει κινητοῦ ᾗ κινητὸν κατὰ γένος ἕκαστον τῶν κατηγοριῶν, οἷον οὐσίας, ποσοῦ, ποιοῦ, φορητοῦ, τῶν ἄλλων· οὕτω γὰρ ἀλλοίωσις, αὔξησις, φορὰ, γένεσις καὶ αἱ ἐναντίαι ταύταις.
Fr. 20 In the second book of *On Motion*: "But more appropriate is that which we both say and is the case: the activity of the potentially movable, insofar as it is movable, according to each genus of the categories, such as substance, quantity, quality, the movable, and the others." For in this way there are alteration, growth, locomotion, generation, and the opposites of these.
Ἐν τῷ τρίτῳ δὲ, οἶμαι, σαφέστερον ταῦτα γέγραφεν· ἐν μὲν τῷ ἀφορισμῷ τῆς κινήσεως τοσαῦτα φαμὲν αὐτῆς εἴδη ὅσαι κατηγορίαι· τὴν γὰρ τοῦ δυνάμει ὄντος ᾗ τοιοῦτον ἐντελέχειαν κίνησιν. Καὶ τοῦτο δὲ ἐν τῷ αὐτῷ βιβλίῳ φησί· Τοῦ δὲ πρός τι κίνησις τοῦ μὲν κατὰ λόγον οὐκ ἔστι, τοῦ δὲ κατὰ δύναμιν ἔστιν· ἡ γὰρ ἐνέργεια κίνησίς τε καὶ καθʼ αὑτό.
But in the third book, I think, he has written these things more clearly: "On the one hand, in the definition of motion, we say that there are as many species of it as there are categories; for the entelechy of that which exists potentially, insofar as it is such, is motion." And he also says this in the same book: "Of the relative, on the one hand, regarding that which is according to ratio, there is no motion, but on the other hand, regarding that which is according to potentiality, there is; for the activity is both a motion and in itself."